Chemical ablation of the left ventricular endocardium reduces ventricular fibrillation inducibility in acute ischemic canine heart

FIGURE 1. Measurement of VF threshold. VF threshold was determined as the minimum current of rectangular pulses that induced VF delivered to the ischemic anterior LV epicardium. See text for detailed explanation. In this example, the rectangular pulses of 5 mA did not provoke any ventricular response and those of 8 mA induced 4 beats of ventricular premature contractions. The current of the rectangular pulses was increased to 9 mA in increments of 1 mA and VF was induced. The measurement was repeated, and the average current that induced VF was determined as the VF threshold. HBE, His bundle electrograms.

FIGURE 2. Changes in VF threshold. VF thresholds before and after LAD ligation and after chemical ablation of the LV endocardium with Lugol's solution (solid line) or normal saline (dotted line) are shown. Decreased VF threshold after LAD ligation significantly increased after chemical ablation with Lugol's solution than with normal saline (p < .01). See text for detailed explanation.

FIGURE 3. Limb leads of the electrocardiogram. Limb leads of electrocardiogram were compared between before (left panel) and after (right panel) chemical ablation of the LV endocardium with Lugol's solution. Note that the QRS duration increased with a left bundle branch block morphology after chemical ablation.

FIGURE 4. Epicardial activation maps before (A) and after (B) LV endocardial chemical ablation. Left panel (a) shows the epicardial activation map of the LV after the LAD ligation and the right panel (b) shows the map after the chemical ablation of the LV endocardium with Lugol's solution. Delayed conduction over the anterior and lateral LV epicardium is noted. See text for detailed explanation. PA, pulmonary artery; LAD, left anterior descending coronary artery; RV, right ventricle; LV, left ventricle; CRUX, crux of the heart, the area on the lower back side of the heart where the coronary sulcus and the posterior interventricular sulcus meet. 14 APEX, apex of heart.

FIGURE 5. Hematoxylin–Eosin stain of chemically ablated endocardium. Lymphocyte infiltration for a depth of 1 mm without any significant changes in the myocardial layer was revealed. There were no clear findings of myocardial ischemia, except for thrombosis in the coronary arteries.